Characterization of sweet potato (ipomoea batatas lam) accessions and their resistance to viral diseases

Abstract

Sweet potato (Ipomoea batatas L.) production contributes significantly to food security worldwide especially in Africa; however, production is constrained by sweet potato viral diseases (SPVD). The use of resistant varieties remains the most effective and reliable method of managing the SPVD. This work sought to explore genetic diversity among 30 sweet potato accessions and to assess their resistance against SPVD in field trial. The field evaluation was based on the randomized complete block design with three replicates and the quantitative and qualitative data were subjected to analysis of variance and DNA PowerMarker. The resulting dendrogram from the morphological characterization separated the 30 accessions into 6 main clusters (A, B, C, D, E and F). Accessions such as CRI-Ogyefo, CRI-Apomuden, CRI-Ligri and CRI-Histarch were found to be closely related. The low mean gene diversity of 0.24 and PIC of 0.21 suggests narrow genetic base across the genome of the 30 sweet potato accessions. Incidence and severity of SPVD did not vary significantly (p>0.05) among the sweet potato accessions, although Faara and CRI-Histarch showed moderate symptoms of virus infection. Viral indexing following grafting unto Ipomoea setosa plant, using nitrocellulose membrane enzyme-linked immunosorbent assay (NCM-ELISA) detected only three (3) viruses, namely, Sweet potato feathery mottle virus (SPFMV), Sweet potato collusive virus (SPCV) and Sweet potato chlorotic stunt virus (SPCSV). All the sweet potato accessions except Blue-blue 3 were infected by at least one of the three viruses detected. Thus, accession Blue-blue 3 is recommended for further screening for virus resistance since presence and absence of the virus may not necessarily mean it is immune to SPVD.